Sleep and stages

Biological Rhythms

•  Annual Cycles: seasonal variations 
• 28 days: menstrual cycle
• 24 hour cycle: our circadian rhythm
• 90 minute cycle: sleep cycles

Circadian Rhythm

•  24 biological clock
•  body temp and awareness changes throughout the day

Sleep Stages

•  90 to 100 mins to pass through the stages
•  Brains waves will change according to the sleep stage you are in
•  First four are known as NREM sleep
•  The fifth stage is called REM sleep

   Stage 1

• Kind of awake and kind of asleep
• Only lasts a few minutes, and you usually only experience it once a night
• Eyes begin to roll slightly
•  Your brain produces Theta Waves (high amp, low frequency) (slow)

   Stage 2

•  This follows Stage 1 sleep and is the "baseline" of sleep
•  This stage is part of the 90 minute cycle and occupies approximately 45-60% of sleep
•  More Theta Waves that get progressively slower
•  Begin to show sleep spindles.. short bursts of rapid brain waves

     Stage 3 and 4

•  Slow wave sleep
•  You produce Delta waves
•  If awoken you will be very groggy
•  Vital for restoring body's growth hormones and good overall health

     Stage 5: REM Sleep

•  Rapid Eye Movement
•  Dreams usually occur in REM
•  Body is essentially paralyzed
•  Composes 20-25% of a normal nights sleep
•  Breathing, heart rate and brain wave activity quicken
•  Vivid dreams can occur
•  From REM, you go back to Stage 2
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